If images are loaded by default, doesn't this open up the old attack vector that delayed image loading was designed to mitigate, wherein a spammer would send separate images to plausible email addresses and use which ones were loaded to build a database of active email addresses. Is it just that Google is confident enough in its spam detection heuristics that it no longer needs this long-standing line of defense?
Unless they open the images even for non-existing accounts, as soon as the mail is received by Google servers. If they are serious about killing the email marketing market they don't control, that's what they should do.
